Stretch-forming apparatus, including a segmental die connected at opposite ends to shiftable vises



R. E. MARTIN Dec. 28, 1948.

STRETCH-FORMING APPARATUS, INCLUDING A SEGMENTA DIE CONNECTED AT OPPOSITE ENDS TO SHIFTABLE VISES 3 Sheets-Sheet 1 Filed Oct. 2, 1946 INVENTOR. Roga? E-Mdrl'lfl flttorney R. E. MARTIN 2,457,483

Dec. 28, 1948.

STRETCH-FORMINGAPPARATUS, INCLUDING A SEGMENTAL DIE CONNECTED AT OPPOSITE ENDS TO SHIFTABLE VISES C N s Shets-Sheet 2 Filed Oct. 2, 1946 um 16mm.

Attorney Dec. 28, 1948.

R. E. MARTIN 2,457,483 STRETCH-FORMING APPARATUS, INCLUDING A SEGMENTAL DIE CONNECTED AT OPPOSITE ENDS TO SHIFTABLE VISES Filed 061;. 2, 1946 3 Sheets- Sheet 3 42 is) a INVENTOR 15 W 9 Royal EQMoJtiD [7 :1" H I BY ATTORNEY Patented Dec. 28, 1948 omrso STATES" PATENT orrice STRETCH FORMING APPARATUS; INCLUD- ING A SEGMENTAL DIE CONNECTED A'll" OPPGSITE ENDS *TO SHIFTABLE VISES Royal EaMartin, Mansfield, Ohio Application OctoberZ, 1945, Serial No. 700,654

.. 5 Claims.

1 1 This invention relatesto stretch-forming apparatus, and particularly relates to apparatus for stretchorming aluminum-or other metal shapes or extruded sections,v such 'as angles, tees, channels, hat channels, etc.

Stretching materials of the a class--- described beyond the elastic limits thereof while being formed has well-known advantages; in that materials formed in this manner will hold-given arcuate shapes without substantial'spring-back. The methods utilized in the past for stretch-forming such materials, however, havebeen generally-un-' satisfactory for various reasons. One method, for example, utilize a pair of relatively fixed vises for gripping opposite ends of-apart'while aseparate die of fixed contour was moved away from the Vises to form-thepart, but this procedure was not entirely satisfactory because of the great difficulty of changing the shape or contour of the die to obtain accurately formed parts, and was also objectionable particularly because of fre. quent breaking or rupturingof the material due to excessive stretching thereof in the area between the gripping vises and the 'die. Other wellknown methods of .forminghave utilized various arrangements of driven rollers or rotary diesy'but. these methods have been. extremely objectionable because they involved the use of .uneconomical cut try forming operations requiring frequent checks hyapplication of the part to a contour orother template. In many instances these rolling for fo example hat channels. ,Qthermethods have similarly been unsatisfactory in various respects.

A general object of this invention-is to provide stretch-forming apparatus of thecharacter described, which is operable ;to ,form they material accurately to desired shape'uonflcontour, :without: the use of so-called cut-and-try? methodsin' forming on a productionbasis; andrainnuserof.

which is obviated rupturingior breaking .of :the. material. due totexcessive stretching applied at lccalizediareasy Anbther =object1ofthe invention. is to provide apparatusof the character describedwhichmay be readily alteredeither to adjust the sh'ape or contour of the 1 parts being produced without necessarily changing the contour or shape of the forming portions of the die, or to interchange the forming "die parts for v producing an entirely dif ferent part.

Another object of "the invention" to {provide apparatus ofthe character "described' wherein r ethods could not -besatisfactorily used .Llng parts of certain cross-section; asfor' (or. 15s 4s) the parts to be formedare substantially uniformly stretchedthroughout the entire lengths thereof.

Another object of the invention is to provide apparatus of the character described 5 fiexible segmental die, and. having improved means for regulating the relative angular velocities. of the segments with respect to each other in proportion to the requisite forming functions thereof.

hr: Another object of the invention is to provide apparatusoft'ne character described including a sectional forming die, having improved take-up means for assuring uniform initial strain on the part when the die is flexed for the forming opera- Etion.

Another-object of the invention is to provide apparatus for stretch-forming parts of the character described which does not require any substantial-degree of skill to operate or adjust.

200? These and otherobjects of the invention will be manifest from the following brief description and the accompanying drawings.

Of theaccompanying drawings:

Figure 1 is a top plan view illustrating stretchforming apparatus embodying the features of the invention, the same being shown in inoperative position.

' Figure 2 is a front elevational view thereof.

Figure 3 is a top plan view ofthe apparatus illustrating improved take-up means for the die segments.

Figure 6 is a fragmentary detail view, partly broken away and in section, taken substantially on the line 5 -5 of Figure 2, and particularly illustrating one of the Vises;

Figure 7 is a cross-section taken substantially on the line 'l'! of Figure 6.

Figure 8 is a top plan view of a modified form of the invention.

Referring particularly to Figures 1, 2 and 3; the numerals. l 0 and VII designate a pair of vises mounted in spaced relation on a fiat support or table. top I2, for restrainingly gripping opposite ends of a part P to be formed. arcuately in a manner .to be described later. The left hand vise H] is pivoted at E3 to a bracket I4 secured to the support l2, to be swingable rearwardly of the supportas viewed in Figures 1 and 3. The right hand vise l l is provided with a U-shaped guide or including a view, as'viewed from the front of the apparatus,

3 retaining member i4, roller iii mounted on a bracket il secured to the top of support 12, whereby the vise H is swingable rearwardly about the center of the roller IE, but the guide member l5 being proportioned to permit lateral relative shifting movement of the vise with respect to the roller 15. The detail construction of ing a hollow cylindrical casing H3, at the inner are shaped correspondingly to the cross-section between, when the blocks are moved together by inwardsliding movement thereof along the guide portions 59 and (see Figures 7 and 8). For slidably retaining the blocks 2| and 22 against the guide surfaces i9 and 20, they may be provided with apertures 23 and 24, in parallelism to 1 the corresponding guide surfaces, in which are slidably received guide pins 25 and 26 fixedly:

, 25 To accomplish axial shifting the blocks 2| and,

secured at 21 and 28 to the interior of casing- 18.

22 toward and from clamping engagement thereof with the 'ends of part P, outwardly axially extending pins 29 and 30 on the outer ends of the blocks 25 and 22 may have spaced retaining portions at their free ends for engaging opposite sides of a plate 3!, which is radially slotted at 32 and 33 for receiving the ends of said pins. Secured to the plate 3| is a rod 34 which extends through a central guide aperture 35 in a removable cap 36 on the outer end of casing 18. The outwardly projecting end of rod 34 is pivoted at 3? to a handle 38, an extension 39 of which is pivoted at 48 to a lug 42 extending outwardly of cap 36. The arrangement is such that the handle as is movable as shown between the full and chain-dotted lines of Figure 7, to move the blocks 2! and 22 in either direction axially of the casing l8. This axial movement of the block, as guided by the pins 25 and 26 and the guide surfaces 19 and 20, causes radial movement of the blocks, with which movement the parts 23 and 3G slide. inthe slots 32 and 33 of plate St.

The handle 38 is movable from the chain-dotted line to the full-line positions thereof shown in Figure 7, to movethe blocks 2! and 22 radially inwardly of each other and thereby to apply requisite clamping or gripping action to the ends of part P. a The clamping mechanism of vise 10 may be substantially the same as that of the vise H.

Mounted between the Vises ID and H may be an elongate flexible forming die 43, which comprises three connected segments 44, 4'5 and 46, or more as desired. The left hand segment 44 is pivoted at 41 to the vise Ill. The right hand end of the right segment 48 is provided with a reduced tapered extension 48 loosely received in a correspondingly shaped strap 49 integrally secured to the'vise H.

The segments 44, and 46 are shown pivotally connected at adjacent ends thereof, at pivot points 553 and 5 l, substantially forwardly of the adjacent rear edge portions of the segments, this inward spacing of the pivot points being a controlling factor withreference to the amount of stretching action applied to the part while being formed. The rearward faces of the segments 44, 45 and 4'53 are arcuately shaped asindicated at 44a 45a andr lta to provide, in the relative positions of the segments shown-in Figure 3, a substantially through which is received a I the vise l I is best illustrated in Figures 5, 6 and '7, the same compris- 1 continuous predeterminately arcuate forming surface portion corresponding to the desired shape of the article to be formed. According to circumstances or requirements, the pivots 5B and 5! may be located at varying distances from said forming portions of the segments, either forwardly or rearwardly thereof The pivotal connection between the segmentsis accomplished by means of vertically extending rounded projections or ribs 52 and 53 at opposite ends of central segment 45, the same being received in correspondingly rounded vertical grooves or sockets 54 and 55 in ends of the outer segments.v The adjacent ends of the segments are oppositely tapered from the pivot points 50 and 5|, as indicated at 55, 56, 51 and 58, whereby the end portions of the segments at opposite forward and rearward sides of the pivots, may limit flexing movement forwardly substantially as shown in Figure 1, or rearwardly as shown in Figure 3. The flexing action of the die 43, during article-forming movement thereof to be described later, applies relatively strong pressure between the projections 52 and 53 and the reciprocal socket'portions 54 and 55, but I otherwise only relativelylight meansis required to hold the segments together. To this end, separation of the segments is prevented by provision of pins 60 onplates 6| secured at the ends of se ments 44 and 46, these pins extending freely into recesses 62, 62 in the upper face of the central segment 45. v

For flexing the die '43 rearwardly, from the inoperative position thereof shown in Figure 1 to the article-forming position thereof shown in Figure 3, a bifurcated link 63, pivoted to the centhe top of support I2, and the segment 45 mat have secured thereto a forwardly extending plate 82 from which depend spaced pins 83 and 84 which engage opposite sides of arcuate guide strip 80. This arrangement is such that engagement of the spaced pins 83'and 84 with the arcuate guidestrip 80, during rearward flexing of the die 43 as urged under power-of the cylinder 19, will effectively control the relative speed of angular movement of the segments about the pivot points 50 and 51, whereby the stretching action of the part P will be substantially uniform along the entire length thereof. Other suitable means may be utilized for controlling the relative angular velocities of the various die segments about the pivots 50 and 5|.

When the straight unformed part P is in place for a forming operation, as shown in Figure 1,

there may be someislack between the segments of' the die 43. In order to take up this slack a releasable wedging device is provided at 85, by which initial compressive force is applied along the die, whereby upon rearwardflexing of the same under pressure to engage the unformed part P the die will start stretching the part immediately.

This wedging mechanism 85 (see Figure'fi may comprise a wedge shaped block 86 which is insertable downwardly between the inner end face Ha f v e H nd. a' apere i face 88. of-a cut-out I portion: 89:-in"the segments: :1 For insertinglandx'i removing the-wedge blockLBBcazlink 90,..piVted-w'I at .29 tito'z-the itop thereof; is..pivotally:c0nnected atQthe .other 1endwat :92'to a handle 93 having a downward :extension 94 "pivotedcto a bracket 95 securedzto the :topof the segment .46.; By means. of -this.arrangementa the .handle. 93Lis operable from :the chain-dotted to .the. full-line positions thereof illustrated Figure 5, to force. the wedge. '86iinto tight engagement between the visa and.

the-segment to take up slack :alongthesegments 44: to r461 .Conversely the :handle is operable. in

theopposite directionto remove thewe'dgeafter.

the-part has been formed; asshown in Figure J 3, tofacilitate reverse flexing 'of the die..and. to

permittmore ready removal of the part. from the visa.

means of screws 97 and 98 threaded through lugs 99.and- 100 on the forward sides of the two end segments. and 46,Jadjacent .the inner ends thereof; These screws are adjustable as desired A desired degreeof. adjustment of the forming curvature of the. die 43 maybe obtained .as by tobeengageable'with'stop projections. I DI and I Eat the/correspondingly.adjacent opposite ends of theintermediatesegment 45, in the operative position of the die illustrated in Figure 3. Thus,

through these screws, the forming curvature of the die-may be altered to correct errors or'accutrusion, such as 'an angle bar for a reinforcing rib of an airplane, a straight length .of extrusion material P is placed in the machine in the manner illustrated in Figure 1, by inserting opposite ends in' the vises I0 and II and applying clamping action thereto by means of handles 38 thereof, substantially as described in connection with Figures '6 and 7. Next, the slack is taken up along the segments 44 to 45 of the die 43, by insertion of wedge 86 in the manner shown in full lines in Figure 5 and as fully described above.

Application of fluid pressure at the forward end of cylinder '19 will move the piston rod 18 rear-" wardly, and ffthrough 'link' 63 attached to central segment 45, will fiex the die 43 rearwardly against theunformed part P until the screws 9! and 98 engage the corresponding stops IUI -and l02 on the central segment. With this rearward flexing,-the-opposite ends of the part P being restrainingly gripped by the vises [G and 1 I, the outer die segments 44 and 46 will jamb tightly against the vises at opposing shoulder portions indicatedat Illa and Ila, and at the same time jambing'pressure Will be applied at the die pivots In the last described condition-the die 43 will be fully flexed, as shown or r fulcrumsu 50 and 5 I.

in Figure 3, and the part Pstret'ch-formed" to finished arcuateshape. I

To facilitate removal of th'e'firiished part from the vises lfl and Ii first thewedging device, best illustrated in Figure 5, is operated through' handle 93 .to remove wedge 86 '(seechain-dotted lines), thereby to relieve the residual strain along the die segments, after which the handles 38 of vises Ill and II are operable to release the clamping blocks 2| and 22. Lateral movement of vise II relatively of segment 46, as permitted by the loose engagement of fixed roller I6 in guard I5, greatly facilitates insertion and removal1*'df%.-therends':of thepart P withirespectltoz.

both vises.

If .upontchecking thefinished part the curva-. ture thereof. is found not to be substantially exact,

the screws :97v and .981may be adjusted forsuca ceeding operations of the machine until the parts areformed accurately.

Al'thoughthe apparatus has been described for use: in. stretch-forming relatively narrow bar;

stock,-:;it will .be readily understood that the apparatus with slight modifications may be utilized for similarly stretch-forming sheet material or. other. material of substantial widths. It will beunderstood also that any number of die segments may be utilized in accordance with particular requirements pertaining, for example, to'the lengths or shapes of the parts.

Referring to Figure 8 of the drawings, there is illustrated a modified form of the invention particularly adapted for forming parts to have an S-bend 'or. other compound curvature.

in two parts indicated atilili and H36, arranged tube at opposite sides of a straight piece of extrusion. angle of other material to be formed.

Each die part liie'and I 06 may comprise a pair of transversely and laterally oppositely arranged die segments. I81, H38, I09 and H0, the central or inwardly adjacent segments It? and I09 being suitably:fixedly mounted on a flat supporting ,-ouslyxdescribed in connection with Figures 1 to 7. Suitably'secured to the outer segments Ina andI i6 maybe oppositely disposed vises H5 and lifisubstantially like the Vises I6 and II described above, for similarly clamping opposite ends of'a straightlength of angle bar P1 or other sectionarmateriaLas shown in full lines. The vises II5fland HG have pivoted thereto, at II! and I I8, links I I9 and H28 theother ends of which are pivoted at I2I and I22 to opposite end of a :bar I23 which is pivoted at I24 intermediate said endsuto'the top-of fixed segment I07.

This "arrangementis su'chthat a link 25 pivotally connected to the barIZis at IN, is adapted towbe': urged 'rearwardly, as by suitable power means (not shown), and through the links H9 and ;I2ii"to :move vises H5 and He in opposite rearward and forward directions, respectively, to the chain-dotted line position of Figure 8. This compound rearward and forward flexing of the die parts I and 35, respectively, as urged by corresponding bending of the opposite ends of the part-Pris efiective to form the part to S-shape corresponding to the curved forming portions of the die segments. In other words, the stretchforming: action of this. form of the invention is substantially equivalent to two oppositelyv arranged flexible dies of the type previously described-in connection with Figures 1 to 7.

The fully formed part P1, illustrated in chaindotted lines in Figure 8, is readily removable by releasing clamping mechanism of vises H5 and H6 in the manner described" above for the firstmentioned form of the invention.

Otherzmodific'aationsxoi the invention may be...

resorted to without departing from the spirit thereof or the scope of the claims.

What is claimed is:

1. Apparatus for stretch-forming metal parts, comprising a support, a pair of vises for releasably gripping opposed ends of a part to be formed,

In this form'of the invention the stretch-iorming'die is means for relatively shiftably mounting said vises on said support to be maintained in predeterminately spaced apart relation restrainingly to hold the unformed part while gripped at said opposed ends thereof, an elongate segmental die connected at opposite ends to said shiftable vises and pro-1 viding part-forming surface portions along the die to be engageable along the length of the unformed. part, the segments of said die being pivotally joined at adjacent ends, the pivot points of adjacent segments being spaced substantially inwardly of said part-forming portions of the die in the direction which would be away from the part, means for positively limiting flexing of said die to provide a predetermined contour along said part-forming portions and power means for flexing said die to said predetermined contour against the part while restrained between said vises.

2. Apparatus for stretch-forming metal parts,

comprising a support, a pair of vises for releasably gripping opposed ends of a part to be formed, means for mounting said vises on said support to be relatively shiftable in opposite arcuate directions while maintained in predeterminately spaced apart relation with respect to a point intermediate said vises restrainingly to hold the unformed part while gripped at said opposed ends thereof, an elongate segmental die connected at opposite ends to said shiftable vises and providing part-forming surface portions along the die to be engageable along the length of the part,

the segments of said die being pivotally joined.

at adjacent ends, the pivot points of adjacent segments being spaced substantially inwardly of said part-forming portions of the die in the direction which would be away from the part, adjustable means for positively limiting flexing of said die to provide a predetermined contour along said part-forming portions, and power means for flexing said die to said predetermined contour against the part while restrained between said vises and thereby to stretch-form said unformed part to acquire said predetermined contour.

3. Apparatus for stretch-forming metal parts, comprising a support, a pair of vises for releasably gripping opposed ends of a part to be formed, means for relatively shiftably mounting said vises on said support to be maintained in predeterminately spaced apart relation restrainingly to hold the unformed part while gripped at said opposed ends thereof, an elongate segmental die connected at opposite ends to said shiftable vises and providing part-forming surface portions along the die to be engageable along the length of the unformed part, the segments of said die being pivotally joined, adjustable means for positively limiting flexing of said die to provide a predetermined contour alongsaid part-forming portions, and power means for flexing said die to said predetermined contour against the part while restrained between said vises and thereby to stretchform said unformed part to acquire said predetermined contour. I

4. Apparatus for stretch-forming metal part comprising a support, a pair of vises for releasably gripping opposed ends of a part to be formed, means for relatively shiftably mounting said vises onisaid support to be maintained in predetermisaid die being pivotally joined with the pivot points being spaced substantially inwardly of said part-forming portions of the die in the direction which would be away from the part, adjustable means for positively limiting flexing of said die to-provide a predetermined contour along said part-forming portions, and power means for flexing said die to said predetermined contour against the part while the same is restrained between said vises and thereby to stretch-form said unformed part to acquire said predetermined contour;

5. Apparatus for stretch-forming metal parts, comprising a support, a pair of vises for releasably gripping a part-to be formed, means for mounting said vises on said support restrainingly to hold the unformed part while gripped at spaced points by the vises, an elongate segmental die connected at opposite ends to said vises and'providing partforming surface portions along the die to be engageable along the length of the part, adjacent ends of the segments of said die being 'pivotally joined with pivot points thereof being spaced substantially inwardly of said part-forming portions of the die in the direction which would be away from the part means at'said adjacent ends of said segments for limiting article-forming flexing of the die to provide a predetermined contour along, said part-forming portions, power means for flexing said die to said predetermined contour against the part while the same is restrained between said vises, guide means on said support for controlling the direction of said flexure of said die, and releasable take-up means for adjusting the slack between said die segments.

I -.ROYAL E. MARTIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS- Number Name Date 242,569 Stevenson June '7, 1881 337,113 Bailey Mar. 2, 1886 457,073 Cliff Aug. 4, 1891 727,959 Johnson May 12, 1903 785,787 Zeh Mar. 28, 1905 829,838 Brown 'Aug. 28, 1906 910,282 Gerlock Jan. 19, 1909 1,264,248 Yoder l Apr. 30, 1918 1,741,840 Harmo n Dec. 31, 1929 1,968,010 Bailey July 31, 1934 2,318,344 Urschel May '4, 1943 2,349,520 I Ripley May 23, 1944 FOREIGN PATENTS Number Country Date 63,933 Norway Sept. 22, 1941 145,857

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